Phase boundary processes for preparing polycarbonates
View Patent ↗Continuous processes for preparing polycarbonates having a weight average molecular weight M w , of 15,000 to 200,000 g/mol, the processes comprising reacting a dihydroxydiarylalkane and phosgene in the presence of a catalyst in a phase boundary process comprising: continuously dispersing in a disperser an organic phase comprising at least a portion of the phosgene and a solvent suitable for the polycarbonate and an aqueous phase comprising the dihydroxydiarylalkane, water and an alkali solution present in an amount of 1.5 to 2.5 moles per mole of the dihydroxydiarylalkane, to form a mixture; reacting the mixture in a first reactor with a residence time of less than 0.5 seconds; further reacting the mixture in a second reactor with addition of further alkali solution and, optionally, a chain terminator; and effecting further condensation in a third reactor with addition of further alkali solution and, optionally, a chain terminator, in the presence of the catalyst.
1. A continuous process for preparing a polycarbonate having a weight average molecular weight M w of 15,000 to 200,000 g/mol, the process comprising reacting a dihydroxydiarylalkane and phosgene in the presence of a catalyst in a phase boundary process comprising:
continuously dispersing in a disperser an organic phase and an aqueous phase to form a mixture, the organic phase comprising at least a portion of the phosgene and a solvent suitable for the polycarbonate, and the aqueous phase comprising the dihydroxydiarylalkane, water and an alkali solution present in an amount of 1.5 to 2.5 moles per mole of the dihydroxydiarylalkane;
reacting the mixture in a first reactor with a residence time of less than 0.5 seconds;
further reacting the mixture in a second reactor with addition of a further amount of an alkali solution and, optionally, a chain terminator; and
effecting further condensation in a third reactor with addition of a second further amount of an alkali solution and, optionally, a chain terminator, in the presence of the catalyst.
2. The process according to claim 1 , wherein the mixture comprises an oil-in-water dispersion.
3. The process according to claim 1 , wherein reacting the mixture is carried out at a temperature of −5° C. to 100° C.
4. The process according to claim 1 , wherein reacting the mixture is carried out at a temperature of 15° C. to 80° C.
5. The process according to claim 2 , wherein reacting the mixture is carried out at a temperature of −5° C. to 100° C.
6. The process according to claim 2 , wherein reacting the mixture is carried out at a temperature of 15° C. to 80° C.
7. The process according to claim 1 , wherein the phosgene is present in an amount of less than 15 mol % excess, based on the dihydroxydiarylalkane.
8. The process according to claim 2 , wherein the phosgene is present in an amount of less than 15 mol % excess, based on the dihydroxydiarylalkane.
9. The process according to claim 5 , wherein the phosgene is present in an amount of less than 15 mol % excess, based on the dihydroxydiarylalkane.
10. The process according to claim 1 , wherein the phosgene is present in an amount of less than 13 mol % excess, based on the dihydroxydiarylalkane.
11. The process according to claim 1 , wherein the dihydroxydiarylalkane comprises one or more selected from the group consisting of 4,4′-dihydroxybiphenyl, 1,1-bis(4-hydroxyphenyl)phenylethane, 2,2-bis(4-hydroxy-phenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and mixtures thereof.
12. The process according to claim 2 , wherein the dihydroxydiarylalkane comprises one or more selected from the group consisting of 4,4′-dihydroxybiphenyl, 1,1-bis(4-hydroxyphenyl)phenylethane, 2,2-bis(4-hydroxy-phenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and mixtures thereof.
13. The process according to claim 5 , wherein the dihydroxydiarylalkane comprises one or more selected from the group consisting of 4,4′-dihydroxybiphenyl, 1,1-bis(4-hydroxyphenyl)phenylethane, 2,2-bis(4-hydroxy-phenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and mixtures thereof.
14. The process according to claim 1 , wherein the disperser comprises one or more selected from the group consisting of nozzles and jet dispersers.
15. The process according to claim 2 , wherein the disperser comprises one or more selected from the group consisting of nozzles and jet dispersers.
16. The process according to claim 1 , wherein the catalyst comprises one or more components selected from the group consisting of tertiary amines, quaternary ammonium salts, quaternary phosphonium salts, and mixtures thereof.
17. The process according to claim 2 , wherein the catalyst comprises one or more components selected from the group consisting of tertiary amines, quaternary ammonium salts, quaternary phosphonium salts, and mixtures thereof.
18. The process according to claim 1 , wherein the disperser comprises a predisperser, a homogenizing nozzle and at least three pumps.
19. The process according to claim 2 , wherein the disperser comprises a predisperser, a homogenizing nozzle and at least three pumps.
20. The process according to claim 5 , wherein the disperser comprises a predisperser, a homogenizing nozzle and at least three pumps.